TABLE 1.

FrbF kinetic parameters (mean ± S.D. of three independent experiments)

Substrate	Km	kcat	Relative activity
	μm	min−1
CMP-5′-3APn	391 ± 61	2.04 ± 0.14	1.0
CMP-5′-H3APn	NDa	ND	6.7b
Acetyl-CoA	19.5 ± 0.4	1.12 ± 0.03c	1.0
Propionyl-CoA	23.6 ± 4.2	0.089 ± 0.024c	0.080 ± 0.022
Malonyl-CoA	ND	ND	0.027 ± 0.006
Acetoacetyl-CoA	ND	ND	0.0044 ± 0.0013
Isobutyryl-CoA	ND	ND	MS
Succinyl-CoA	ND	ND	MS

^a ND, not determined; MS, below UV detection limit (product observed by MS/MS only).

^b Substrate was generated in situ with 10-fold excess FrbG.

^c k_cat was measured at 400 μm CMP-5′-3APn.